Entecavir, [1S-(1α,3α,4β)]-2-amino-1,9-dihydro-9-[4-hydroxy-3-(hydroxymethyl)-2-methylenecyclopentyl]-6H-purin-6-one monohydrate, is currently being used as a drug for treating hepatitis B viral infections.
Entecavir and its use as an antiviral agent are described by Zahler et al. in U.S. Pat. No. 5,206,244. Improved processes of preparing entecavir are described by Bisacchi et al., in WO 98/09964, and by Penchi et al., in WO2004/052310 and US20040192912. The disclosure of each of the foregoing patent or patent applications is herein incorporated by reference in its entirety.
Colonno et al. in WO 01/64221 describe compositions containing a low dose of entecavir administered on a daily basis to treat hepatitis B virus infection and/or co-infections.
The discussion of the background to the invention herein is included to explain the context of the invention This is not to be taken as an admission that any of the material referred to was prior art as at the priority date of any of the claims.